Syncope
Nancy Drucker, MD
Syncope - BASICS
Syncope - description
Loss of consciousness, typically lasting no longer than 1–2 minutes, due to a transient drop in cerebral perfusion pressure
Syncope - general prevention
- Avoiding circumstances predisposing to the most common form of syncope (vasovagal)
- Sitting or lying down when warning signs occur
- Maintaining adequate hydration, especially during illness/exertion
Syncope - pathophysiology
- Most common mechanism is vasovagal or neurocardiogenic, in which a variety of stimuli and conditions—pain, dehydrated state, emotional upset, carotid pressure—trigger increased vagal tone, leading to slowed heart rate and peripheral vasodilation and decreased cerebral perfusion.
- Rarer causes include cardiac arrhythmia (heart block or tachyarrhythmia) and intracranial hypertension.
Syncope - etiology
- Underlying causes of syncope in any age group may include congenital heart malformations; arteriovenous malformation; pulmonary hypertension; intracranial hypertension due to hydrocephalus, mass, or pseudotumor; and tachyarrhythmia or heart block (Stokes–Adams).
- Other causes of syncope by age group include the following:
- Toddlers:
- Pallid or cyanotic breath-holding spells; these occur in response to pain, excitement, or frustration, begin with a deep inspiration or exhalation, although the precipitating “gasp” may not be apparent. (Anemia may be associated.)
- Mastocytosis: Syncope preceded by dyspnea
- Older children:
- Prolonged QT syndrome or arrhythmogenic right ventricular dysplasia; may be familial; may occur as unprovoked syncope or as exercise-induced syncope that may resemble an epileptic convulsion
- Adrenal insufficiency
- Dysautonomia, orthostatic hypotension
Syncope - associated conditions
>1/3 of syncopal spells in children are accompanied by a convulsion (nonepileptic) that usually lasts <1 minute (EEG shows normal findings).
Syncope - DIAGNOSIS
Syncope - signs & symptoms
Loss of consciousness
Syncope - history
- Detailed history of the spell is the most important information used to distinguish syncope from seizure or head trauma.
- Questions addressing a possible family history of sudden death, seizures, or syncope are essential: A family history of sudden death, syncope, or seizures should trigger further laboratory studies.
- The child or observers may recall “presyncopal” signs—such as warmth, diaphoresis, light-headedness, nausea, palpitations, or visual changes—all lasting only a few seconds before loss of consciousness.
- Syncope during exercise or without warning may indicate an underlying arrhythmia.
- Increasing duration of unconsciousness suggests increasing probability that the event is epileptic, rather than syncope.
- Caution: Syncope may trigger a convulsion in an epileptic patient.
- Epilepsy may rarely mimic a syncopal episode or recurrent presyncopal symptoms; “temporal lobe syncope” seems to occur principally in adults or adolescents.
- Generalized tonic–clonic movements may occur with syncope—presyncopal signs point to the nonepileptic nature of the event.
- Details of body position, eye movements, and respiratory pattern
- Carbon monoxide poisoning may cause syncopelike spells; ask about potential exposure.
Syncope - physical exam
Key findings to document include the following:
- Vital signs, peripheral/central pulses
- Orthostatic pulse and BP changes
- Right and left arm BPs
- Funduscopy: Possible papilledema
- Cranial bruits
- Heart sounds (gallop, click, significant murmur)
Syncope - tests
Pitfall: Recurrent syncope due to prolonged QT interval may be missed on routine EKG; QT interval may be prolonged only on treadmill testing or cardiac monitoring.
Syncope - lab
- Some children may have a clear history of vasovagal syncope, and no laboratory testing will be required. If the event is suspected to be symptomatic of a heart condition, cardiological evaluation (electrocardiogram) may be useful.
- Children with unexplained syncope may undergo more extensive testing to rule out arrhythmia: Treadmill electrocardiogram, Holter monitoring, EEG (looking for evidence of epilepsy)
- Other laboratory testing (glucose, CBC, blood gases, brain imaging, spinal tap) may be appropriate based on clinical suspicion of underlying causes (see “Differential Diagnosis”).
Syncope - differencial diagnosis
Alternative causes of loss of consciousness not due to syncope include:
- Head trauma
- Epilepsy (“temporal lobe syncope”)
- Psychogenic
- Stroke, hypoglycemia (rare except in certain metabolic disorders)
Syncope - TREATMENT
Syncope - general measures
- Clinical intervention is aimed primarily at training the patient in prevention/anticipation:
- Avoiding circumstances predisposing to the most common form of syncope (vasovagal)
- Sitting or lying down when warning signs occur
- Maintaining adequate hydration, especially during illness/exertion
- Therapy is otherwise addressed to underlying causes, in the unusual circumstance that one is found.
- Syncope with exercise always warrants a cardiovascular evaluation, with EKG and electrocardiogram.
Syncope - FOLLOW UP
- Many children experience a developmental stage in which for unknown reasons they have frequent vasovagal episodes; they may retain a tendency to syncopal spells through adulthood.
- Persistent and frequent spells may prompt more extensive laboratory testing, as described above.
Syncope - bibliography
- Batra AS, Hohn AR. Consultation with the specialist: Palpitations, syncope, and sudden cardiac death in children: Who’s at risk? Pediatr Rev. 2003;24:269–275.
- Friedman MJ, Mull CC, Sharieff GQ, et al. Prolonged QT syndrome in children: An uncommon but potentially fatal entity. J Emerg Med. 2003;24:173–179.
- Kapoor WN. Syncope. N Engl J Med. 2000;343:1856–1862.
- McVicar K. Seizure-like states. Pediatr Rev. 2006;27(5):e42–e44.
- Rodriguez-Nunez A, Fernandez-Cebrian S, Perez-Munuzuri A, et al. Cerebral syncope in children. J Pediatr. 2000;136:542–544.
- Sapin SO. Autonomic syncope in pediatrics: A practice-oriented approach to classification, pathophysiology, diagnosis, and management. Clin Pediatr. 2004;43:17–23.
- Strickberger SA, Benson DW, Biaggioni I, et al. AHA/ACCF scientific statement on the evaluation of syncope. Circulation. 2006;113:369–370.
Syncope - CODES
Syncope - icd9
780.2 Syncope
Syncope - FAQ
- Q: Do breath-holding spells cause brain damage?
- A: Pallid breath-holding spells appear to be uniformly benign; in rare cases, older children with cyanotic breath-holding spells have had neurologic sequelae of recurrent hypoxemia.
- Q: What limitations in activity are appropriate for children with recurrent syncope who have normal heart structure and function?
- A: Precautions should be taken similar to those for children of similar age who have epilepsy—closely monitored water recreation and restrictions on climbing; however, most children with recurrent syncope do not experience spells in the midst of vigorous activity.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
Other Book Chapters Related to Syncope
Read excerpts from these other book chapters related to Syncope:
Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Williams & Wilkins.
More About Causes of Syncope
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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